The invention relates generally to rolls and more particularly to a hydraulically supported roll having controllable line pressure.
A roll having controllable line pressure is known from DE-P No. 30 03 395. In rolls of this type the annular clearance gap between the crosshead and inner circumference of the hollow roll is subdivided by longitudinal seals arranged along the crosshead on both sides of the effective plane of the roll between crosshead and inner circumference of the hollow roll and past which the inner circumference of the hollow slides. The longitudinal seals divide the annular clearance gap into two semi-circular longitudinal chambers with one longitudinal chamber located on the side of the roll gap and the other longitudinal chamber positioned on the side located opposite the roll gap. The longitudinal chamber on the side of the roll gap can be filled with pressurized fluid and the pressure acting against the inner circumference of the hollow roll generates the line pressure in the roll gap. Zones of decreased pressure are provided in this longitudinal chamber and form irregularities in the otherwise uniform pressure distribution therein through which the line pressure can be modified by controllably reducing the pressure in the zones. Pressurization of only one of the two longitudinal chambers produces the line pressure in the roll gap which may be modified by the decreased pressure zones.
The invention provides an improved hydraulically supported hollow roll by elimination of the complicated and more costly longitudinal chamber-seal arrangement of prior hydraulically supported rolls while still providing for the generation and modification of line pressure in the roll gap.
In DE-No. 30 03 395 in the gap between the crosshead and inner circumference of the hollow roll, the longitudinal chamber located on the side of the roll gap is provided with pressurized fluid which generates a uniform pressure against the inner circumference of the hollow roll and thus a corresponding line pressure since the other longitudinal chamber is not pressurized. However, in the invention, the pressurized fluid in the gap between the crosshead and the inner circumference of the roll does not act solely along one side against the roll gap to generate the line pressure or a portion thereof. Rather, the pressurized fluid acts uniformly in all directions over the entire circumference of the hollow roll since no longitudinal seals have been provided. The effect of this pressure without the additional measures provided by the invention would be neutral and the hollow roll would not be externally affected at all.